1. Field of the Invention
The present application relates to a windmill having vanes that automatically withdraw from the wind to protect the windmill from over speed in high winds and redeploy when winds lessen.
2. Description of the Prior Art
Conventional agricultural water windmills are observed to be susceptible to damage during high wind conditions, particularly during the downburst gust events of thunderstorms. In the conventional design, a number of metal vanes are balanced about a horizontal axis. The damage from high wind conditions can occur in the form of thrown vanes. High rotational speed develops excessive stress in the connectors holding the vanes to the axis, and at a critical speed some of these connectors break. The remaining vanes are no longer balanced, causing high shaking forces on the windmill axis. These shaking forces can damage attached machinery, such as the pump and other down-hole components.
The design concept proposes to eliminate this damage sequence by incorporating a passive control system into the windmill. The passive control system limits the maximum rotational speed, preventing large centrifugal forces from causing vane detachment.
None of the prior art, taken either singly or in combination, is seen to describe the instant invention as claimed.